A commercially known air filter of an air intake system of a combustion engine of a motor vehicle has a filter housing composed of a housing pot and a housing lid. The housing lid can be removed from the housing pot in order to open the filter housing. The filter housing has an inlet for air to be cleaned and an outlet for cleaned air. A round filter element is arranged in the filter housing such that it separates the inlet from the outlet. The round filter element has a filter medium for filtering the air that surrounds an element interior space in relation to an element axis in a circumferentially closed manner. The filter element is arranged in an exchangeable manner in the filter housing.